Hydrocarbon wells, horizontal wells in particular, typically have wellscreen sections having a perforated inner tube with an overlying screen portion. The purpose of the screen is to block the flow of particulate matter into the interior of the production tubing. Despite the wellscreen, some contaminants and other particulate matter still enter the production tubing. The particulate matter usually occurs naturally or is part of the drilling and production process. As the production fluids are recovered the particulate matter is also recovered at the surface. The particulate matter causes a number of problems in that the material is usually abrasive reducing the life of any associated production equipment. By controlling and reducing the amount of particulate matter that is pumped to the surface, overall production costs are reduced.
Even though the particulate matter may be too large to be produced, the particulate matter may cause problems at the downhole wellscreens. As the well fluids are produced the larger particulate matter is trapped in the filter element of the wellscreens. Over the life of the well as more and more particulate matter is trapped in the filter elements the filter elements will become clogged and restrict flow of the well fluids to the surface.
A method of reducing the inflow of particulate matter before it reaches the wellscreens is to pack gravel or sand in the annular area between the wellscreen and the wellbore. Packing gravel or sand in the annulus provides the producing formation with a stabilizing force to prevent any material around the annulus from collapsing to produce particulate matter and it also provides a pre-filter to stop the flow of particulate matter before it reaches the wellscreen.
In certain gravel packing operation a screen with a detachable member, a crossover tool, and packer are run into the wellbore together. Once the screens, crossover tool, and packer are properly located the packer is set so that it forms a seal between wellbore and the screen isolating the annular region above the packer from the annular region below the packer. The bottom of the screen is sealed so that any fluid that enters the screen should pass through the screening or filtering material.
The crossover tool has a port that directs all fluid flow from inside of the tubular to the outside of the tubular including the screens below the crossover. The crossover tool has a second port that allows fluid to flow from the interior area of the screen below the crossover tool to an annular area around the exterior of the tubular but above the packer.
Once the packer is set, a slurry, usually containing gravel, may be pumped down the well through the tubular. When the slurry reaches the crossover tool it exits the crossover tool below the crossover tool and into the annular space created on the outside of the screen.
As the slurry travels from the top of the well toward the bottom along the outside of the screen the gravel is deposited as the transport fluid that carries the gravel drains to the inside of the screen. As the fluid drains into the interior of the screen it becomes increasingly difficult to pump the slurry down the wellbore. Once a certain portion of the screen is covered the gravel will start building back from the bottom towards the top to completely pack off the screen.
After the annular area around the screen has been packed with gravel then the operator releases the packer and crossover tool from the detachable member and reverses out. After the packer and crossover tool have been released a detachable member will remain as a reconnection point. The detachable member is required to allow the operator to reconnect to the liner before the well is put into service.
Generally, some type or mechanical packer or packoff mechanism is used to seal the annulus inside the well casing and outside of the liner so that all flow is directed through the gravel pack and into the liner. This prevents flow up the annulus which could remove the gravel pack sand from around the liner. Typically the packer is run in as a separate device that attaches to the detachable member with the production tubing attached above the packer. This assembly must be run into the well, attached to the liner and then mechanically or hydraulically actuated to seal the device to the annulus. The time to run these sealing mechanisms as well as the cost of these tools can be significant.
There exists, therefore, a significant need for an improved packer assembly for use in gravel pack operations that can eliminate additional trips downhole. The present invention fulfills these needs and provides further related advantages.